A typical cyclone separator is usually associated with a fluidized bed reactor and includes a vertically-oriented, cylindrical vortex chamber in which is disposed a central gas outlet pipe for carrying the separated gases upwardly, while the separated solids are returned to the fluidized bed through a funnel-shaped base of the separator via a stardpipe. These vertical cyclone separators are substantial in size and eliminate the possibility of a compact system design which can be modularized and easily transported and erected. For larger reactors, several vertical cyclone separators are often required to provide adequate particle separation, which compound the size problem and, in addition, usually require complicated gas duct arrangements with reduced operating efficiency.
Horizontal cyclone separators characterized by a horizontally-oriented, cylindrical vortex chamber, as disclosed, for example, in U.S. Pat. No. 5,174,799, have been constructed which eliminate many of the above mentioned problems. For example, horizontal cyclone separators may be readily configured within the upper portion of the reactor and integrated with the walls of the reactor making the bulk, weight, and cost much less than conventional separators. Additionally, they can be modularized making them easy to erect. However, many known horizontal cyclone separators have various shortcomings, particularly with regard to their gas-solids inlet which extends substantially the full length of the separator. This extended length causes the separated solids that have collected on the wall past the exit to become re-entrained in the incoming gas-solids stream. Another shortcoming is that the vertical end wall opposite the gas outlet causes the separated solids to bounce off the latter wall and become re-entrained in the separated gas stream.